Sulfate DOC SulfaVer 4 Method 1. Method (0 70, and mg/l) Powder Pillows. Test procedure

Transcription

1 DOC SulfaVer 4 Method 1 Method (0 70, and mg/l) Powder Pillows Scope and Application: For oil and gas field waters. 1 Adapted from Standard Methods for the Examination of Water and Wastewater. USEPA accepted for reporting wastewater analysis Test procedure 1. Push PRGM. The display shows PRGM? Initial setup: go to Instrument Setup on page 3 to add the program to the instrument. 2. Push 128 ENTER. The display shows mg/l, SO4 L, SO4 M or SO4 H and the ZERO icon. 3. Push CONC to select the test range: SO4 L: 0 70 mg/l SO4 M: mg/l SO4 H: mg/l 4. Add the specified sample volume to a clean sample cell: SO4 L: 10 ml SO4 M: 1.0 ml SO4 H: 0.1 ml Note:Use a TenSette or glass pipet to measure 0.1 ml or 1.0 ml. 5. If the sample volume is less than 10 ml, add deionized water to the 10-mL line. Tighten the cap on the sample cell and invert to mix. Note:A 10-mL graduated mixing cylinder can be used in steps 4 and Put the sample cell in the cell holder. Put the instrument cap over the sample cell. 7. Push ZERO. The cursor moves to the right, then the display shows: 0 mg/l SO4 and L, M or H 8. Remove the cap and add the contents of one SulfaVer 4 Reagent Powder Pillow to the sample cell. Tighten the cap and invert to mix. Note:The sample will become cloudy if sulfate is in the sample. Note:Accuracy is not affected by undissolved powder. Page 1

2 9. Push TIMER ENTER A 5-minute reaction period starts. Do not move the sample cell during the reaction period. 10. Within five minutes after the timer beeps, put the prepared sample in the instrument. Put the instrument cap over the sample cell. 11. Push READ. The cursor moves to the right, then the result in mg/l sulfate is shown. Notice! Do not push the CONC key at the end of the test to change the range. The result is applicable only to the test range that was selected in step 3. Clean the sample cells with soap and a brush. Note:For best results use the Standard Adjust option. Refer to Standard Adjust on page 3. Sampling and Storage Collect the sample in a clean plastic or glass bottle. Samples can be used for up to 28 days if they are kept at or less than 4 C (39 F). Let the sample temperature increase to room temperature before analysis. Interferences Known interferences are shown in Table 1. The interference levels are applicable to an undiluted 10-mL sample. The interference levels increase proportionally as the sample is diluted. Table 1 Interferences Substance Barium Interference Level Interferes at all levels. The greater the barium concentration compared to the sulfate concentration, the greater the error. Samples with high barium concentrations will generally give a result that is 20% lower than the actual sulfate concentration. Calcium 20,000 mg/l as CaCO 3 Chloride 40,000 mg/l as Cl - Magnesium 10,000 mg/l as CaCO 3 Silica 500 mg/l as CaCO 3 Turbidity Filter samples that have a high level of turbidity Accuracy Check Standard Additions Method Use the standard additions method to validate the test procedure, reagents and instrument and to find if there is an interference in the sample. 1. Fill three sample cells with sample as specified in steps 4 and 5 of the test procedure. 2. Use a TenSette Pipet to add 0.1, 0.2 and 0.3 ml of a 1000 mg/l Standard Solution to the sample cells. Mix fully. 3. Complete the test procedure for each sample. Page 2

3 4. Review the results. The sulfate concentration should increase by 10 mg/l for SO4 L, 100 mg/l for SO4 M or 1000 mg/l for SO4 H for each 0.1 ml of standard that is added. 5. If the concentration does not increase by the correct amount, refer to Standard Additions in Section 1 of the procedures manual. Standard Solution Method Use a 50 mg/l Standard Solution to validate the test procedure, reagents and the instrument. Select the SO4 L test range in step 3 and use 10 ml of the standard solution instead of the sample in step 4. To adjust the result, refer to Standard Adjust. To prepare this standard solution, add 5.0 ml of a 1000 mg/l Standard Solution to a 100- ml volumetric flask. Dilute to the mark with deionized water and mix fully. Standard Adjust The standard adjust option is recommended when program 128 is used. 6. Measure the concentration of a 50 mg/l Standard Solution. Select the SO4 L range and use 10 ml of the standard solution. Keep the sample cell in the instrument. 7. Push the SETUP key and use the arrow keys to scroll to the STD option. 8. Push ENTER. Method Performance 9. Push the numbers 50 to make the instrument read the value of the standard solution concentration. 10. Push ENTER to complete the adjustment. Note: The MR and HR calibration curves are adjusted proportionally when the SO4 L calibration curve is adjusted. Refer to Section 1, Standard Curve Adjustment of the procedures manual. Precision In a single laboratory, with a 50 mg/l sulfate standard solution, two representative lots of powder pillows and the instrument, a single operator got a standard deviation of ± 0.5 mg/l sulfate. Estimated Detection Limit (EDL) The EDL for program 128 SO4 L is 4.9 mg/l SO 4. For more information on derivation and use of the estimated detection limit, refer to Section 1 of the procedures manual. Summary of Method ions in the sample react with barium in the SulfaVer 4 Reagent to make an insoluble barium sulfate precipitate. The amount of precipitate is proportional to the sulfate concentration. The SulfaVer 4 also contains a stabilizing agent to hold the precipitate in suspension. Instrument Setup This procedure adds program 128 to a DR/820, DR/850 or DR/890 instrument. 1. Push the ON key to turn on the instrument. 2. Push the SETUP key. 3. Push the down arrow key until the prompt line shows USER. 4. Push the ENTER key. 5. Push the numbers 8138, then push ENTER. Page 3

4 6. Refer to Table 2. Find the number from the Enter column that corresponds to Line Number 1 on the display. Push these numbers on the keypad, then push ENTER. Continue to add the numbers that correspond to each line number on the display. Note: Use the arrow keys to scroll and review or change numbers at any time. Table 2 Instrument setup Line Number Enter Line Number Enter Page 4

5 REQUIRED REAGENTS AND APPARATUS Description Quantity Per Test Units Item No. SulfaVer 4 Reagent Powder Pillows 1 pillow 100/pkg Sample Cell, ml, with cap 1 6/pkg OPTIONAL REAGENTS Description Units Item No. Standard Solution, 50 mg/l 500 ml Standard Solution, 1000 mg/l 500 ml Water, deionized 4 L OPTIONAL APPARATUS Description Units Item No. Cylinder, graduated mixing, 10 ml Filter Paper, folded, 12.5 cm 100/pkg Flask, volumetric, 100 ml, Class A Funnel, poly, 65 mm Pipet, TenSette, 0.1 to 1.0 ml Pipet Tips, for Pipet 50/pkg Pipet, TenSette, 1.0 to 10.0 ml Pipet Tips, for Pipet 50/pkg Pipet, volumetric, 5.00 ml, Class A Pipet Filler, safety bulb Page 5

6 FOR TECHNICAL ASSISTANCE, PRICE INFORMATION AND ORDERING: In the U.S.A. Call toll-free Outside the U.S.A. Contact the HACH office or distributor serving you. On the Worldwide Web HACH COMPANY WORLD HEADQUARTERS Telephone: (970) FAX: (970) Hach Company, All rights reserved. Printed in U.S.A. 06/2012, Edition 2